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packet: only test po->has_vnet_hdr once in packet_snd

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Packet socket option po->has_vnet_hdr can be updated concurrently with
other operations if no ring is attached.

Do not test the option twice in packet_snd, as the value may change in
between calls. A race on setsockopt disable may cause a packet > mtu
to be sent without having GSO options set.

Fixes: bfd5f4a3d6 ("packet: Add GSO/csum offload support.")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2017-09-26 12:20:17 -04:00 committed by David S. Miller
parent 4971613c16
commit da7c956101
1 changed files with 3 additions and 1 deletions
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4
net/packet/af_packet.c
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@ -2840,6 +2840,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
struct virtio_net_hdr vnet_hdr = { 0 };
int offset = 0;
struct packet_sock *po = pkt_sk(sk);
bool has_vnet_hdr = false;
int hlen, tlen, linear;
int extra_len = 0;
@ -2883,6 +2884,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
err = packet_snd_vnet_parse(msg, &len, &vnet_hdr);
if (err)
goto out_unlock;
has_vnet_hdr = true;
}
if (unlikely(sock_flag(sk, SOCK_NOFCS))) {
@ -2941,7 +2943,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
skb->priority = sk->sk_priority;
skb->mark = sockc.mark;
if (po->has_vnet_hdr) {
if (has_vnet_hdr) {
err = virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le());
if (err)
goto out_free;